Production of aluminum chlorid.



UNITED sra'rns Parana anion.

FRANZ VON KO'GELGEN, OF HOLCOMBS ROCK, VIRGINIA, AND GEORGE O. SEWARD, OF EAST ORANGE, NEW JERSEY, ASSIGNORS T0 VIRGINIA LABORATORY COMPANY, 01 NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PRODUCTION OF ALUMINUM CHLORID- No Drawing.

county of Essex and State of New Jersey,

have jointly invented certain new and useful Improvements in the Production of Aluminum Chlorid, of which the following is a specification.

This invention relates to the production of aluminum chlorid from clay or bauxite, which are the cheapest raw materials avallable. -The production from such materials,

and by a cheap process, of aluminum chlorid,

would render practicable the production of aluminum by the electrolysis of such chlorid.

The invention also affords a means for the refining of clay or bauxite or analogous material by removing the iron or iron compounds contained therein. It also provides a means for separating aluminum and silicon in materials where the oxids or compounds of these elements are associated.

Aluminum chlorid has heretofore been produced according to the method of De-' ville, by mixing alumina with carbon and a suitable binder, forming briquets, and treating them in a retort with chlorin. Since pure alumina was used for this purpose, pure aluminum 'chlorid was formed. Gin (E Zectromet. Ind. April 1904:) applied this method to bauxite. He got a chlorid which was contaminated with all the iron .which was present in the bauxite, and also some silicon, and in a. special receiver silicon tetra-chlorid. The latter wasdecomposed into SiO and HCl by steam. .The raw material according to this method is mixed with enough carbon to reduce all the constituents of the bauxite.

We have found that the chlorin hasa decidedly selective action onthe constituents of bauxite and clay and a long series of ex .periments showed'us that the chlorination can be conducted so that the constituents are chlorinated one after the'other and silica left behind. In the ores of alumina the main constituents are iron oxid, alumina and silica. quantities.

Titanium is present but in small As the chlorination is carried on, first the Specification of Letters Patent.

Patented'July 2'7, 1915.

Application filed November 26, 1913. Serial No. 803,206.

other chlorination furnace, where the chlorination is resumed. Now alumina is'chlorinated and the silica is left behind, if the chlorination is stopped at the right time.

In experimenting withbauxite and kaolin and also with the different oxids we found that the selective action of chlorin can be materially assisted by a regulation of temperature during the chlorination. We found the following facts:

(a) Iron oxid mixed with carbon was appreciably chlorinated at 300 (3., but the action was slow. At 400 C. a perfect chlorination took place.

(b) Silica mixed with carbon was not chlorinated between 400 and 800. At

900 a treatment of two hours chlorinated (0) Aluminum oxid mixed with carbon was scarcely chlorinated at all at 400. The chlorination started at 500. Thereaction was quickened as the temperature rose, and at 900 was substantially complete. g

((1) Titanium oxid mixed with carbon is chlorinated very slowly at 5 00 and at 7 00 is completely chlorinated. It is not only he selective action of the chlorin but the temperature which allows it to chlorinate 'one constituent of the ore,

while the other remains practically untouched.- v 1 v The process of chlorination of bauxite or clay is conducted therefore as follows :We

heat the material mixed with reducing material at a temperature between300 and 450.

:During this geriod iron .is chlorinated andits chlorid caug tin a receiver, while the other ingredients remain ractically untouched. We then heat up the mace to 900, whereby all the iron chlorid which was not driven over to the receiver, will be volatilized. Then we change the receiver and start the chlorin v again, whereby the chlorination of alumina commences. .Th'e titanium will be chlorinv ated too, but being so much more volatile than the aluminum chlorid, is caught separately. It is advisable not to try to exhaust the bauxite or clay of alumina, but the limitation of temperature at 900 helps'materially to leave the silica untouched.

Instead of changing the receiver it may be desirable to have two different furnaces, which are kept at different temperatures. I11 that case, when the chlorination of iron is over, the material is removed into the other chlorination furnace, where the temperature is kept at 900.

The process described above could be conducted in retorts heated externally, but the fact that the outside of the vessel must be kept hotter than the material itself, does not allow a long life for the apparatus, the retort being deteriorated rapidly. \Ve propose to use either a large vessel which is heated internally by electricity, or, to. in-I. troduce with the chlorin air, for which car-,

bonaceous material is provided in the interior of the apparatus, and'cause the burning of this material by the.air to furnish the heat necessary to keep the reaction going.

e use either dilute chlorin, such as is obtained .in the electrolytic decomposition of chlorids when the electrolytic furnace is not kept tightly closed, so that air is mixed with the chlorin; or we introduce the air separately. In the latter case we may introduce it simultaneously with the chlorin or at intervals. We may introduce it also at a different place than the chlorin. The main object with this kind of chlorination is to create heat in the material itself without seriously heating the walls, and this is best done by introducing air into thematerial and providing carbonaceous fuel to be burned by the air. As the fuel we may use either a solid material or as.

We have used in practice intermittent heating. We interrupted the chlorin introduction during the internal heating, and we also stopped the heating while the chlorin was applied. This was done in order to have the chlorin as concentrated as possible. We found it very desirable to preheat the chlorin.

Ifin the practice. of the process a small amount of silicon chlorid should be found (which'is-always likely to occur to a minute extent), and should be carried over with the aluminum chlorid, the product can be washed with carbon tetrachlorid which will entirely dissolve out such traces of silicon chlorid. It ispossiblealso that in some cases traces of titanium. chlorid maybe found in the product, andth'ese may be eliminated by the same washing with carbon. tetrachlorid.

A" suitable manner "of conducting the process is the following:-P1ace the clay or bauxite in small pieces in a tower and heat by either externallyor internally-applied heat until the moisture is eliminated; then introducechlorin either alone or with some reducing gas. -The iron is chlorinated and driven out as chlorid with perhaps a small amount of aluminum cl1lor1d.- Then the hot mass of bauxlte is discharged mto another apparatus and there is quickly mixed with enough heat to keep the reaction going. As,

the reaction is exothermic, much heat is not required, but we have to supply enough to keep the material at bright red heat.

Another way of effecting the selective action of chlorin on the constituents of bauxite or clay would be to form briquets of the material with enough carbon to reduce alumina and iron oxld. The purification of the raw material would be effected then so that the reaction in the first tower is interrupted as soon as the chlorination of iron is over. In this case we would get some AlCl with the FeCl, which must be afterward separated from it in a distinct apparatus. .The temperature must be regulated as pointed out above. The material freed from iron will be dumped then directly into the second tower, where the real chlorination begins. In this case a mixing with carbon isnot necessary, since the briquets have the materials in the right proportion and the chlorination can proceed at once after the material is transferred from one apparatus to the other.

The process provided by our invention is susceptible of considerable modification or.

variation in its performance.- It will be understood thatthe carbonaceous or other reducing a ent employed serves in the case of heating by internal combustion two functions, namely, that of reducing first the iron oxid or compound and then thealu-minum oxid or compound, and secondly, as a fuel the combustion of which occasions internal generation of heat; and that the first of these functions requires a restriction or deficiency of the reducing material in order to limit the process to the reduction of iron and alumina, while the second requires an excessof reducing agent or fuel beyond that required for the performance of the first function. The desired result may be attained by controlling the process rather than by the preliminary determination of the precise amount of reducing agent; that is to say, by varying the admission of air the proportion of reducingagent burned as fuel may be controlled so that, while an amplev form or as a liquid which may be sprayed into the vessel, or as a gas, or partly in one form and partly in another. Instead of using a tower as the chlorination chamber, the latter may be like any of the numerous horizontal roasting furnaces.

llhat we claim is 1. In the production of aluminum chlorid from bauxite or clay, subjecting the raw material to a partial chlorination at a temperature below 500 to remove iron.

2. The production of aluminum chlorid from bauxite or clay by subjecting the raw material to a partial chlorination while heating to a temperature of approximately 900 C. substantially as described.

3. The production of aluminum chlorid from bauxite or clay by subjecting the heated material to the influence of chlorin first at a temperature below 500 C. to remove iron and then to a temperatureof approximately 900 C. to separate alumina from silica. L

4. The production of aluminum chlorid, by mixing the raw material with sullicient carbonaceous material to reduce compounds of iron and aluminum, but not silicon, removing iron by subjecting the raw material while heated to a temperature below 500 C. to the action of chlorin for a limited time, until the iron is eliminated, and then treating the product at a temperature approximating 900 C. with chlorin until the alumina is converted into chlorid.

The process which consists in mixing clay or bauxite with sutiicient carbonaceous material to reduce compounds of iron and aluminum, heating the material to a tem perature below about 500 C. in the presence of chlorin until the iron is eliminated, then removing to another apparatus and heating to a temperature approximating 900 C. in the presence of chlorin to produce aluminum chlorid.

6. The process which consists in heating 7. The process which consists in heating clay or bauxite mixed with a reducing agent in presence of chlorin at a temperature below 500 until iron is substantially eliminated.

S. The production of aluminum chlorid from bauxite or clay by subjecting the raw material to a partial chlorination with a reducing agent while heating it to a suitable temperature substantially as described.

9. In the production of aluminum chlorid by chlorination. internally supplying the necessary heat for the chlorination by introducing air and an equivalent proportion of fuel to cause combustion inside of the ap mratus.

10. In the production of aluminum chlorid by chlorination, internally supplying the necessary heat for the chlorination by an excess of reducing agent beyond what is necessary for the partial chlorination, and introducing air enough to burn such excess, to maintain a temperature ap n-oxiniating 900 C.

11. The production of aluminum chlorid by mixing with the raw material a carbonaceous reducing agentdlcating the material in the presence of chlorin, introducing air whereby to burn a portion of such carbonaceous material and thereby internally heat the mass, and discontinuing the process after the production of aluminum chlorid diminishes and before the material production of silicon chlorid.

12. The production of aluminum chlorid by chlorinating a mixture of bauxite or clay with carbon and intermittently heating the furnace internally by burning fuel inside by introducing air in alternation with the chlorin substantially as described.

In witness whereof, we have hereunto signed our names in the presence of two subscribing witnesses.

FRANZ VON KUGELGEN. GEORGE O. SEIVARD.

Witnesses CHARLES K. FRASER, FRED Turns. 

